SHADE TREES AND THEIR INSECT DEFOLIATORS. 



FOUR PRINCIPAL LEAF-EATERS. 



There are four insects principally concerned in the defoliation of the 

 shade trees in the city of Washington. They are : (1) The Imported 

 Elm Leaf-beetle {Galeruca xanthomelccna) ; (2) the Bag- worm {Thyridop- 

 teryx ephemerceformis); (3) the White-marked Tussock-moth (Orgyia 

 leucostigma) ; and (4) the Fall Web-worm {Eypliantria cunea). 



THE IMPORTED ELM LEAF-BEETLE. 



{Galeruca xanthomelccna* Schrank.) 



The depredations of this pest have bow become widely extended 

 throughout the ^Northeastern States, rendering almost worthless and 

 unsightly those most valuable shade trees of our cities— the elms. As 

 its injuries are so far unknown iu the Mississippi Valley, the blighted 

 appearance of the elms on the Department grounds in midsummer, and, 

 especially of the European varieties, at once attracted our attention 

 when we first came to Washington, and a series of experiments was be- 

 gun with a view of checking the ravages of the insect. The excellent 

 opportunites thus offered for experiment and study have since been im- 

 proved, and, with some prefatory passages in relation to the history 

 and habits of the beetle, we will give the practical results reached. 



AN IMPORTATION FROM EUROPE. 



This beetle has done great mischief in the Old World, especially in 

 Germany and France, and it is very important that the public know 

 the best method of coping with it here. According to Glover, it was 

 imported as early as 1837. Its distribution was formerly confined to 

 limited areas near the coast, and its earlier attacks were notably about 

 Baltimore and Xew Jersey. 



HABITS AND NATURAL HISTORY. 



The general characteristics of this insect have been pretty well stud- 

 ied abroad. Mr. E. Heegerf has given an excellent account of its 



life-history, with a detailed description of the larva and figures illus- 



, . - 



* This is the Galeruca cratagi Forst., and G. cahnariensis Fabr. In Crotch's Check- 

 list it appears as Galerucella xanthomelcena. 



t Seventieth contribution to the natural history of insects. Sitzungsberichte der 

 kais. Ac. Wiss., Wien, 1858, vol. 29. 

 8 



